Characterization of two monoclonal antibodies raised in Btk(xid) mice thatrecognize phosphorylcholine-bearing antigens from Trichinella and other helminths

This study investigated the binding properties of two monoclonal antibodies (mAbs US1 and US2) raised in (CBA/n x BALB/c)F-1 (NBF1) Btk(xid) male mice . Both mAbs show unusual specificity for phosphorylcholine (PC)-containing TSL4 antigens of Trichinella Specifically, and in contrast to mAbs raised i n normal mice, US1 and US2 mAbs do not bind to artificial PC-protein conjug ates and are not inhibited by either free PC or NPPC, although US2 was part ially inhibited by NPPC at high concentration (10(-2) M). However both mAbs completely abrogate the binding to Trichinella antigens of other anti-PC m Abs (e.g. BH8 and Mab-2). These results suggest that both US1 and US2 recog nize complex PC-containing epitopes. The patterns of recognition of PC-bear ing antigens from different helminths by US1, US2, Mab-2 and BH8 were broad ly correlated with phylogenetic proximity. The closest similarities were ob served between the members of the Trichinelloidea superfamily (Trichinella spiralis and Trichuris muris) and among the ascarids (Toxocara canis, Anisa kis simplex, Hysterothylacium aduncum and Ascaris lumbricoides). However; U S1 did not react with the filarial nematode Onchocerca volvulus and reacted only weakly with Onchocerca gibsoni, while US2 reacted only weakly with bo th species. Only BH8 recognized PC-bearing antigens fi om the trematode Fas ciola hepatica and the cestode Bothriocephalus scorpii. These results sugge st that PC is attached to identical or very similar structures on most diff erent nematode species, although major differences exist with respect to he lminth species from groups such as the trematodes and cestodes that are phy logenetically distant from the nematodes.